Without limiting the scope of the invention, its background is described in connection with fluid handling and more particularly, to an improved apparatus and method for plugging a tubular bore.
After tubing and piping is manufactured, it is often necessary or desirable to protect the interior of the tubing and piping from the outside environment. This may especially be true if threads have been machined into the interior end surfaces of the tubing or piping. Furthermore, after tubing or piping is installed for its intended purpose, it is often necessary to pressure test the system to ensure that all the piping or tubing is properly joined so that there will be no leaks when the system is placed into service. Additionally, it is often desired to maintain a positive pressure on the tubes or piping to prevent corrosion or other damage to the interior of the tubes while they are being stored or shipped or during construction, such as providing an internal gas purge during welding.
The prior art teaches many different types of plugs that have been designed to plug the ends of the tubular bores of pipes and tubing. U.S. Pat. No. 5,771,937 a device for plugging a pipe includes a resilient, hollow body member that expands with the application of internally applied pressure to block the pipe, much like blowing up a balloon inside of a tubular bore. This system requires a source of compressed air or other gas to inflate the balloon.
U.S. Pat. No. 5,119,861 a device is disclosed for plugging a pipe that comprises an elastomer seal. The resilient elastomeric seal is attached to the perimeters of two axially aligned rigid end plates. This device relies upon the elasticity of the elastomeric seal to draw the end plates together while radially expanding so as to engage and seal against the inner wall of a tubular bore. This device lacks any means for tightening the seal beyond the force exerted by the elastomer as the elastomer is allowed to relax from a stretched position.
U.S. Pat. No. 4,968,197 a device is disclosed that includes a disc-like screw plate, an elastic sealing ring, a horn-like pressure block and a lifting eye. The screw plate receives the bottom edge of the sealing ring and the horn-like pressure block is mounted on the upper edge. The screw plate has a central rod that extends upwardly through a hole in the pressure block. The lifting eye is then threaded received on the end of the rod and as the lifting eye is turned, the block and plate are urged together causing the sealing ring to expand against the internal wall of a pipe.
The present inventors had also previously submitted U.S. Patent Application 20040074549 directed to a Bore Plug, now expired.